Friction properties of polyvinyl alcohol hydrogel measured by pendulum type tribometer

Abstract

Polyvinyl alcohol hydrogel (PVA-H) is expected as an artificial articular cartilage. In this study, a pendulum type tribometer was manufactured to imitate the joint movement of human body. A sus304 stainless steel ball with the diameter 35mm was slid to concave PVA-H with the same radius of curvature to the mating ball. The PVA-H specimen was formed by 5 repeated thaw-freeze cycles. The normal load and period of pendulum was 200N and 0.5 Hz, respectively. The PVA-H and ball was slid under saline lubricant at room temperature. Since the principle of this tribometer is pendulum, the oscillation amplitude decreased as the experiment duration progress. On the other hand, the oscillation period was the same even if the test duration. As a result, the coefficient of friction at the end of the test reached around 0.01, though initial coefficient of friction represented around 0.08.